1. Field of the Invention
The present invention relates to enhancing the visibility of portable warning devices and, particularly, to increasing the conspicuousness of manually supported warning signs. More specifically, this invention is directed to improvements in and to warning signs of the type commonly employed in construction areas and, especially, to the incorporation of a periodically energized illuminated message into a manually supported warning sign. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
2. Description of the Prior Art
It is common practice to employ "flag men" to control traffic flow in highway construction zones. These individuals manipulate passive signs which bear short, lettered, instruction messages, i.e., "SLOW" or "STOP". The instructions are usually provided on opposite planar sides of a sign board, and that sign board is typically mounted on the top of a pole, the opposite end of the pole being positioned on the ground. The instruction transmitted to an approaching motorist is thus changeable by simply rotating the pole so that the appropriate message is presented to approaching traffic.
For many reasons, including the fact that construction zones are often characterized by a dusty environment which reduces visibility, there has been a long standing desire to increase the noticeability of portable warning signs of the type briefly described above. Obviously, any such visibility enhancements must be accomplished without significantly increasing the size and weight of the sign. Maintenance of portability has previously dictated that electrically energized devices, i.e., light sources, not be used in such signs because the power requirements for such light sources would require unduly large and heavy batteries.